Re: [PATCH v9 3/3] PCI/ACPI: Use device constraints to decide PCI target state fallback policy

[Limonciello, Mario]

On 8/4/2023 8:17 AM, Mika Westerberg wrote:
> On Thu, Aug 03, 2023 at 08:02:29PM -0500, Mario Limonciello wrote:
> > +/**
> > + * acpi_pci_device_constraint - determine if the platform has a contraint for the device
> > + * @dev: PCI device to check
> > + * @result (out): the constraint specified by the platform
> > + *
> > + * If the platform has specified a constraint for a device, this function will
> > + * return 0 and set @result to the constraint.
> > + * Otherwise, it will return an error code.
> > + */
> > +int acpi_pci_device_constraint(struct pci_dev *dev, int *result)
> > +{
> > +	int constraint;
> > +
> > +	constraint = acpi_get_lps0_constraint(&dev->dev);
> > +	pci_dbg(dev, "ACPI device constraint: %d\n", constraint);
> > +	if (constraint < 0)
> > +		return constraint;
> > +	*result = constraint;
>
> Is there something preventing to return the constraint directly instead
> of storing it into "result"?

My aim was to make the caller use it a pass/fail function.

I'll adjust it so that the caller would look for >= 0 instead.

> > +
> > +	return 0;
> > +}
> > +
> >   static void acpi_pci_config_space_access(struct pci_dev *dev, bool enable)
> >   {
> >   	int val = enable ? ACPI_REG_CONNECT : ACPI_REG_DISCONNECT;
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 60230da957e0c..6c70f921467c6 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -1082,6 +1082,14 @@ static inline bool platform_pci_bridge_d3(struct pci_dev *dev)
> >   	return acpi_pci_bridge_d3(dev);
> >   }
> >   
> > +static inline int platform_get_constraint(struct pci_dev *dev, int *result)
>
> Ditto here.
>
> > +{
> > +	if (pci_use_mid_pm())
> > +		return -ENODEV;
> > +
> > +	return acpi_pci_device_constraint(dev, result);
> > +}
> > +